.\" -*- nroff -*-
.\" Copyright 2013 Los Alamos National Security, LLC. All rights reserved.
.\" Copyright 2010 Cisco Systems, Inc.  All rights reserved.
.\" Copyright 2007-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.\" $COPYRIGHT$
.TH MPI_Lookup_name 3 "Jun 10, 2020" "4.0.4" "Open MPI"

.SH NAME
.nf
\fBMPI_Lookup_name\fP \- Finds port associated with a service name

.fi
.SH SYNTAX
.ft R

.SH C Syntax
.nf
#include <mpi.h>
int MPI_Lookup_name(const char *\fIservice_name\fP, MPI_Info \fIinfo\fP,
	char *\fIport_name\fP)

.fi
.SH INPUT PARAMETERS
.ft R
.TP 1.4i
service_name
A service name (string).
.TP 1.4i
info
Options to the name service functions (handle).

.SH OUTPUT PARAMETERS
.ft R
.TP 1.4i
port_name
a port name (string).
.TP 1.4i
IERROR
Fortran only: Error status (integer).

.SH DESCRIPTION
.ft R
This function retrieves a \fIport_name\fP published under
\fIservice_name\fP by a previous invocation of MPI_Publish_name. The
application must supply a \fIport_name\fP buffer large enough to hold
the largest possible port name (i.e., MPI_MAX_PORT_NAME bytes).

.SH INFO ARGUMENTS
The following keys for \fIinfo\fP are recognized:
.sp
.sp
.nf
Key                   Type      Description
---                   ----      -----------

ompi_lookup_order     char *    Resolution order for name lookup.
.fi

The \fIompi_lookup_order\fP info key can specify one of four valid
string values (see the NAME SCOPE section below for more information
on name scopes):

.TP 4
\fIlocal\fP: Only search the local scope for name resolution.
.TP 4
\fIglobal\fP: Only search the global scope for name resolution.
.TP 4
\fIlocal,global\fP: Search the local scope for name resolution.  If
not found, try searching the global scope for name resolution.  This
behavior is the default if the \fIompi_lookup_order\fP info key is not
specified.
.TP 4
\fIglobal,local\fP: Search the global scope for name resolution.  If
not found, try searching the local scope for name resolution.
.PP
If no info key is provided, the search will first check to see if a
global server has been specified and is available. If so, then the
search will default to global scope first, followed by local. Otherwise,
the search will default to local.

.SH NAME SCOPE
Open MPI supports two name scopes: \fIglobal\fP and \fIlocal\fP. Local scope
values are placed in a data store located on the mpirun of the calling
process' job, while global scope values reside on a central server. Calls
to MPI_Unpublish_name must correctly specify the scope to be used in
finding the value to be removed. The function will return an error if
the specified service name is not found on the indicated location.
.sp
For a more detailed description of scoping rules, please see the MPI_Publish_name
man page.

.SH ERRORS
.ft R
Almost all MPI routines return an error value; C routines as
the value of the function and Fortran routines in the last argument. C++
functions do not return errors. If the default error handler is set to
MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism
will be used to throw an MPI::Exception object.
.sp
Before the error value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job, except for
I/O function errors. The error handler may be changed with
MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN
may be used to cause error values to be returned. Note that MPI does not
guarantee that an MPI program can continue past an error.
.sp
See the MPI man page for a full list of MPI error codes.

.SH SEE ALSO
.ft R
.nf
MPI_Publish_name
MPI_Open_port


